Small business owners are driving a continuing increase in the adoption of cash balance retirement plans, and those plans are leaving growth of new 401(k)s in the dirt.

According to the 2017 cash balance research report from Kravitz, Inc., the number of new cash balance plans increased in 2015, the most recent year for which complete IRS Form 5500 is available, by 17 percent, while 401(k)s only grew by 3 percent. The industry only expected an estimated growth rate of 12 percent to 15 percent in the sector.

In addition, total assets in cash balance plans expanded to $1.1 trillion, as they've logged double-digit growth every year since 2001. In fact, over the past 15 years, cash balance plans — driven by small business owners — have increased from 2.9 percent to 34 percent of all defined benefit plans. Between 2010 and 2015 alone, the nationwide growth rate of new plans hit 152 percent.